Digital Health, Biology and Earth: Part VI

Chairman

Selma Souihel – BIOVISION

Talk 1

Title:Canard Mediated (De)Synchronization in Coupled Phantom Bursters

Speaker:
Elif Koksal – Mathneuro

Abstract:
Collective dynamics of coupled slow-fast oscillators have a great importance in the context of physiology when microscopic and macroscopic levels can be represented as relaxation oscillators. Synchronization of multiple timescale systems may involve synchrony of fast timescale dynamics, spikes, and/or slow timescale dynamics. In this presentation, we focus on the effect of canards on collective dynamics of an extended version of a neuroendocrine model which accounts for the alternating pulse and surge pattern of gonadotropin releasing hormone secretion. The model is formed by two FitzHugh-Nagumo oscillators that evolve on different timescales, with a feedforward coupling from the slow one (regulator) to the fast one (secretor). Global and local features of the resulting 4D three timescale model have been studied in the context of slow-fast dynamics and MMOs where folded singularities and associated canard trajectories have a particular importance. For instance, so-called secondary canards due to a folded node are responsible for the presence of a plateau with small oscillations in the model output, after the surge and before the pulsatility resumption. We extend the model to 6D by adding one more secretor and focus on the slow-fast transitions in the presence of coupling. We explore the influence of the relationship between canard structures and coupling on patterns of synchronization and desynchronization. We propose two different sources of desynchronization, induced by canards near a folded node and canards near a folded saddle, respectively.

Talk 2

Abstract:Computer models of the heart are of increasing interest for clinical applications due to their discriminative and predictive abilities. However the number of simulation parameters in these models can be high and expert knowledge is required to properly design studies involving these models, and analyse the results. In particular it is important to know how the parameters vary in various clinical or physiological settings. In this paper we build a data-driven model of cardiovascular parameter evolution during digestion, from a clinical study involving more than 80 patients. We first present a method for longitudinal parameter estimation in 3D cardiac models, which we apply to 21 patient-specific hearts geometries at two instants of the study, for 6 parameters (two fixed and four time-varying parameters). From these personalised hearts, we then extract and validate a law which links the changes of cardiac output and heart rate under constant arterial pressure to the evolution of these parameters, thus enabling the fast simulation of hearts during digestion for future patients.

2:00 pm: Perception, Cognition and Interaction: Part I

Talk 1

SpeakerOnur Tasar (TITANE)

TitlePOLYGONIZATION OF BINARY BUILDING CLASSIFICATION MAPS USING MESH APPROXIMATION WITH RIGHT ANGLE REGULARITY

AbstractOne of the most popular and challenging tasks in remote sensing applications is the generation of digitized representations of Earth’s objects from satellite images. A common approach to tackle this challenge is a two-step method that first involves performing a pixel-wise classification of the satellite images, then vectorizing the obtained classification. In this talk, I will explain the proposed approach to vectorize input binary building classification map by optimizing a labeled triangle mesh, which minimizes an objective function that balances between fidelity to the classification map in L1 norm sense, right angle regularity for polygonized buildings, and final mesh complexity.

Talk 2

SpeakerJohanna Delanoy (GRAPHDECO)

TitleHow to make computers understand human sketches? An introduction to sketch based modeling

AbstractModeling an object in 3D can be a tedious process since it requires a good knowledge of the software and of the modeling process. On the other hand, sketching is a very natural way to represent objects. The ambition of sketch-based modeling is to bring the ease and immediacy of sketches to the 3D world. However, while humans are extremely good at perceiving 3D objects from line drawings, this task remains very challenging for computers. In this talk, I will present various strategies that have been developed to simplify this problem in order to build interactive sketch based modeling systems. I will then present our new approach which tries to overcome existing limitations by using deep learning at the core of our system.

Speaker

Title

Tracking technologies and protection of your privacy on the Web

Abstract

We all use the Web every day. While we browse the Web, numerous companies are spying on our online activities by using Web technologies: they collect information about pages we visit, buttons we click and text we type. Having all this information collected, they show us advertisements or may ask us to pay a higher price during online shopping. In this talk, I will talk about privacy on the Web, and I will answer the following questions: - Why we should not say “I have nothing to hide” and we should be concerned with our online privacy? - Why once I searched for a product to buy, this product is “following” on every site I visit? - What are the techniques companies use to track me across websites? - How can I protect myself from companies tracking my activities online?